A Dibenzofuran-Based Host Material for Blue Electrophosphorescence

Vecchi, Paul A.; Padmaperuma, Asanga B.; Qiao, Hong; Sapochak, Linda S.; Burrows, P. E.

doi:10.1021/ol0614121

Cited by 211 publications

(151 citation statements)

References 11 publications

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“…The operating voltages of A and B were much lower than those of FIrpic-based PHOLEDs with p-DBFDPO as the host, for which 800 cd cm À2 can be achieved at 5.4 V. [33] This also demonstrates the stronger carrier injection ability of o-DBFDPO relative to p-DBFDPO, which can be attributed to the stronger polarisation effect of short-axis substitution and further confirms the conclusions of optical and theoretical calculation analysis. It was shown that devices A and B have almost identical brightness/voltage (B/V) characteristics.…”

Section: à2supporting

confidence: 78%

“…DSC analysis shows that the melting point (T m ) of o-DBFDPO is 356 8C (Figure S1, inset in the Supporting Information), which is nearly 170 8C higher than that of o-DBFDPO and attributable to the enhanced p-p intermolecular interaction. Significantly, the glass transition temperature (T g ) of o-DBFDPO is as high as 191 8C, about 100 and 90 8C higher than those of o-DBFPPO [43] and p-DBFDPO, [33] respectively, and is outstanding among the small molecular hosts. Obviously, the symmetrical structure of o-DBFDPO greatly improves the thermal performance.…”

Section: Resultsmentioning

confidence: 99%

“…[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] It has been established that the P=O moieties not only serve as insulating linkages but also modify the electrical properties of the molecules as a kind of electron-withdrawing group. [33] PO hosts are thus believed to represent both good carrier injection/ transporting capabilities and high T 1 values. Nevertheless, it is notable that nearly all of the PO hosts reported so far have been produced through substitution with P=O moieties along the long axes of the chromophores, which also influences the T 1 values and limits the complicated modification of PO hosts.…”

Section: Introductionmentioning

confidence: 99%

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A New Phosphine Oxide Host based on ortho‐Disubstituted Dibenzofuran for Efficient Electrophosphorescence: Towards High Triplet State Excited Levels and Excellent Thermal, Morphological and Efficiency Stability

Han

Xie

et al. 2011

Chemistry A European J

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An efficient host for blue and green electrophosphorescence, 4,6-bis(diphenylphosphoryl)dibenzofuran (o-DBFDPO), with the structure of a short-axis-substituted dibenzofuran was designed and synthesised. It appears that the greater density of the diphenylphosphine oxide (DPPO) moieties in the short-axis substitution configuration effectively restrains the intermolecular interactions, because only very weak π-π stacking interactions could be observed, with a centroid-to-centroid distance of 3.960 Å. The improved thermal stability of o-DBFDPO was corroborated by its very high glass transition temperature (T(g)) of 191 °C, which is the result of the symmetric disubstitution structure. Photophysical investigation showed o-DBFDPO to be superior to the monosubstituted derivative, with a longer lifetime (1.95 ns) and a higher photoluminescent quantum efficiency (61 %). The lower first singlet state excited level (3.63 eV) of o-DBFDPO demonstrates the stronger polarisation effect attributable to the greater number of DPPO moieties. Simultaneously, an extremely high first triplet state excited level (T(1)) of 3.16 eV is observed, demonstrating the tiny influence of short-axis substitution on T(1). The improved carrier injection ability, which contributed to low driving voltages of blue- and green-emitting phosphorescent organic light-emitting diodes (PHOLEDs), was further confirmed by Gaussian calculation. Furthermore, the better thermal and morphological properties of o-DBFDPO and the matched frontier molecular orbital (FMO) levels in the devices significantly reduced efficiency roll-offs. Efficient blue and green electrophosphorescence based on the o-DBFDPO host was demonstrated.

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Section: à2supporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Phosphine Oxide Host based on ortho‐Disubstituted Dibenzofuran for Efficient Electrophosphorescence: Towards High Triplet State Excited Levels and Excellent Thermal, Morphological and Efficiency Stability

Han

Xie

et al. 2011

Chemistry A European J

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“…[5][6][7] Phosphine oxide-based electron transport materials have also been reported and triphenylphosphine oxide has been used as an electron transport material and found to decrease the driving voltage of OLEDs. 8,9 Spiro-type derivatives containing fluorene and benzofluorene have received a great deal of attention as fluorescent materials for OLEDs, because asymmetrical spiro compounds having naphthalene groups can not only preserve their inherent characteristics, such as their morphological stability, high glass transition temperature and amorphous properties, but also provide a variety of substituents on the aromatic ring of the spiro molecules, resulting in the formation of conjugation controlled OLED host and dopant materials.…”

Section: Introductionmentioning

confidence: 99%

Orange Phosphorescent Organic Light-emitting Diodes Using a Spirobenzofluorene-type Phospine Oxides as Host Materials

Jeon¹,

Lee²,

Lee³

et al. 2010

Bulletin of the Korean Chemical Society

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Spiro-type orange phosphorescent host materials, 9-diphenylphosphine oxide-spiro[fluorene-7,9'-benzofluorene] (OPH-1P) and 5-diphenylphosphine oxide-spiro[fluorene-7,9'-benzofluorene] (OPH-2P) were successfully prepared by a lithiation reaction followed by a phosphination reaction with diphenylphosphinic chloride. The EL characteristics of OPH-1P and OPH-2P as orange host materials doped with iridium(III) bis(2-phenylquinoline)acetylacetonate (Ir(pq)2acac) were evaluated. The electroluminescence spectra of the ITO (150 nm)/DNTPD (60 nm)/NPB (30 nm)/ OPH-1P or OPH-2P: Ir(pq)2acac (30 nm)/BCP (5 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm) devices show a narrow emission band with a full width at half maximum of 75 nm and λmax = 596 nm. The device obtained from OPH-1P doped with 3% Ir(pq)2acac showed an orange color purity of (0.580, 0.385) and an efficiency of (14 cd/A at 7.0 V). The ability of the OPH-P series to combine a high triple energy with a low operating voltage is attributed to the inductive effect of the P=O moieties and subsequent energy lowering of the LUMO, resulting in the enhancement of both the electron injection and transport in the device. The overall result is a device with an EQE > 8% at high brightness, but operating voltage of less than 6.4 V, as compared to the literature voltages of ~10 V.

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“…Moreover, the neighboring hole-and electron-transporting materials should have higher TE than that of the blue phosphor [6] to prevent the triplet exciton quenching. However, these kinds of materials are rare and hard to design [7,8]. Based on a conventional blue phosphorescent dopant and their host materials, a common approach of improving the performance is to optimize the emitting layer (EML), such as introduction of a mixed-host architecture [9,10], double hosts [11], and stepwise EML [12][13][14][15][16], and so on.…”

mentioning

confidence: 99%

Improved efficiency of blue phosphorescence organic light‐emitting diodes with irregular stepwise‐doping emitting layers

Wang

Huang

et al. 2013

Physica Status Solidi (a)

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We demonstrate highly efficient blue phosphorescence organic light-emitting diodes (PHOLED) with irregular stepwisedoping emitting layers (EMLs). High efficiency is realized by inserting a high-doping EML between two relatively lowdoping EMLs. Peak luminous efficiency and power efficiency of 19.2 cd A À1 and 18.0 lm W À1 are achieved, while those of a continuous stepwise-doping device are 9.8 cd A À1 and 8.6 lm W À1 . The dramatic efficiency enhancement is mainly attributed to the high hole-electron recombination probability and suppressed triplet excitons quenching by fine tuning the doping concentrations in the EMLs.

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A Dibenzofuran-Based Host Material for Blue Electrophosphorescence

Cited by 211 publications

References 11 publications

A New Phosphine Oxide Host based on ortho‐Disubstituted Dibenzofuran for Efficient Electrophosphorescence: Towards High Triplet State Excited Levels and Excellent Thermal, Morphological and Efficiency Stability

A New Phosphine Oxide Host based on ortho‐Disubstituted Dibenzofuran for Efficient Electrophosphorescence: Towards High Triplet State Excited Levels and Excellent Thermal, Morphological and Efficiency Stability

Orange Phosphorescent Organic Light-emitting Diodes Using a Spirobenzofluorene-type Phospine Oxides as Host Materials

Improved efficiency of blue phosphorescence organic light‐emitting diodes with irregular stepwise‐doping emitting layers

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